gistfile1.py

class StudentImportUploadForm(forms.Form):
    import_file = forms.FileField(required=True)
    importer = lo.Importer(
        lo.SkippingIterator(3),
        lo.HeadersMapper([
            'first_name',
            'last_name',
            'email',
            'birthday',
            'phone',
            'gender',
            'grade',
            'german_is_mother_tongue',
            'has_individual_german',
            'has_individual_math',
            'has_individual_english',
            'has_individual_french',
            'has_individual_sciences',
        ]),
        UploadedRecordForm,
    )

    @classmethod
    def sniff_format(cls, fh):
        for reader in (lo.XLSXReader, lo.CSVReader.reopen):
            try:
                row_iterator = reader(fh)
                break
            except Exception:
                fh.seek(0)
        else:
            raise Exception('File format not supported')
        return row_iterator

    @classmethod
    def parse_file(cls, fh):
        reader = cls.sniff_format(fh)
        return cls.importer(reader)
    
    def clean_import_file(self):
        import_file = self.cleaned_data['import_file']
        try:
            self.parse_file(import_file)
        except lo.InvalidFileException as e:
            raise forms.ValidationError(_('Invalid file. {0}'.format(e)))
        else:
            return import_file
        finally:
            import_file.seek(0)